青藏高原北麓河地区典型热融湖塘周边多年冻土特征研究

Permafrost Features around a Representative Thermokarst Lake in Beiluhe on the Tibetan Plateau

青藏高原多年冻土区广泛分布着热融湖塘,热融湖塘的形成会对周边的多年冻土产生显著的影响.选取北麓河地区一典型热融湖,运用探地雷达技术对该湖塘周边的多年冻土进行了探测.结果表明:湖岸坍塌剧烈区一侧的多年冻土上限深度大于湖岸轻微坍塌区和湖岸稳定区,并且在湖水的热作用下,湖岸多年冻土的上限深度随离湖岸距离的减小而增大;湖岸坍塌剧烈区上限附近的地下冰含量也明显高于湖岸轻微坍塌区和湖岸稳定区.同时,通过对湖岸测温孔的地温观测数据的分析可以看出,湖岸地温正在逐年升高且升高的速率快于天然状态,湖岸地温随离湖岸距离的减小逐渐增大.

A large number of thermokarst lakes are widespread in the Tibetan Plateau and greatly influence the permafrost around these lakes.In this paper,a thermokarst lake in Beiluhe is taken as an example and ground penetrating radar（GPR） sounding was performed to study the permafrost around the Lake.It is found that the permafrost table in the severe lakeshore-collapsed area is deeper than that in slight collapsed area and stable area.Under the influence of thermokarst lake,the depth of the permafrost table around the lake is also varying with the distance to the lakeshore,somewhat deeper near the lakeshore.Moreover,the content of underground ice in the severe lakeshore-collapsed area is more than that in other areas.In addition,the analysis of the ground temperature in the borehole near the lakeshore indicates that the ground temperature of the lakeshore is also increasing and the ground temperature near the lakeshore is higher than that far from the lakeshore.